There are several
compelling reasons for DOE to sequence Pseudomonas syringae.
This is a very versatile organism with several important phenotypes
that have made it a focus of study and commercial application that
is relevant to the mission of DOE. This species is a plant pathogen,
causing disease on a variety of plant species, severely impacting both
food and biomass production. The DOE through its Energy Biosciences
division has supported considerable work on basic aspects of virulence
determinants in this pathogen over the years in labs such as that of
Dr. Brian Staskawicz at Berkeley as well as other work at Cornell University,
the University of Wisconsin, UC-Riverside, and elsewhere.

The DOE supported
work has emphasized the gene-for-gene relationship that exists in this
host-pathogen system and has led to the cloning of plant-disease resistance
genes in tomato and other plants. The elucidation of the genome sequence
of P. syringae would greatly aid such studies by better enabling
new approaches to the study of coordinate gene expression in the pathogen
in response to plant genotypic differences.

The DOE has also
supported work on the elucidation of genes involved in stress tolerance
of P. syringae in my lab at Berkeley for many years. Because
this bacterium lives in stressful conditions on leaves there has been
interest in finding those genetic determinants for stress tolerance
that is enhanced in this species. The study of genes expressed in response
to stresses on plants would be greatly advanced by the genome sequence
of P. syringae. In addition, work at Berkeley has identified
many genes which are expressed only when the bacterium is on plants.
Such genes represent an extensive "hidden genome" that is unexplored
because it is not expressed in culture. The availability of the genome
sequence for P. syringae would greatly expand the ability to
look at coordinate expression of such genes, in situ, such as by using
microarray-based techniques.

Strains of P.
syringae have also been exploited for a variety of industrial
purposes of significance to DOE. For example, many strains of this
species are active as ice nuclei catalyzing ice formation at temperatures
approaching 0 C. For this reason they have been exploited as artificial
ice nucleating agents in processes such as those involved in artificial
snow production. A major use of the freeze-dried cells of P. syringae used
in such an application has been in the creation of artificial ice
islands to facilitate offshore oil drilling in cold oceans such as
in the arctic. In a similar application there has been interest in
using such ice nucleation active bacteria for the production of artificial
mountains of ice in the winter for use in summer cooling of large
industrial and office buildings. There is also considerable activity
in the study of the use of such bacterial ice nuclei in improving
the process of freezing of various foods, including frozen emulsified
foods such as ice cream to improve both the energy efficiency of
the process and quality of the product. Again, a more thorough knowledge
of the genetics of P. syringae that would accompany a genomic
sequence would help in exploiting this species for such uses.

Since the DOE has
already initiated a Pseudomonas fluorescens genomic project,
the sequencing of the Pseudomonas syringae genome would be of
great value in a comparative analysis of these genomes. By comparing
the genomes of these Pseudomonads with one another and with
species such as Pseudomonas aeruginosa it should help establish
which gene sets are unique to specialization in host or environmental
niche. Thus the value of a given genomic sequence increases dramatically
with the number of related sequences that are made available; P.
syringae would make a good organism to compare with these other Pseudomonas.